动态疲劳荷载作用下路面混凝土力学性能研究

发布时间：2018-09-04 18:19

【摘要】：为了探究经历车辆动态疲劳荷载作用后路面水泥混凝土力学性能的衰减规律,基于正交试验设计了力学性能、耐久性及工作性最佳的路面混凝土配比;选取了30%、50%、80%三个荷载应力水平,设计了4种不同的疲劳加载方案对路面混凝土进行疲劳试验。利用MTS测定了不同疲劳加载方案下路面混凝土的剩余强度和应力-应变曲线变化规律,并借助经典的断裂能理论对动态疲劳荷载作用下路面混凝土力学性能进行研究。结果表明:应力水平为80%的动态疲劳荷载作用下路面混凝土的剩余弯拉强度呈现衰减趋势,加载4h后其剩余弯拉强度较基准降低了20%;当荷载应力水平为30%、50%时,动态疲劳荷载作用前期混凝土剩余弯拉强度出现负衰减,疲劳加载3h后其剩余弯拉强度较基准分别提高7.9%、3.1%;动态疲劳荷载造成路面混凝土脆性增加,其变形呈现"弹性-塑性-类似弹性"的三阶段衰减规律;路面混凝土的断裂能随着加载时间及荷载应力水平的增加逐渐降低,应力水平大于50%时疲劳荷载对混凝土的断裂能劣化显著;当应力水平为30%、50%和80%时,加载4h后断裂能较基准分别降低24%、57%和66%。
[Abstract]:In order to investigate the attenuation law of the mechanical properties of pavement cement concrete after the dynamic fatigue loading of vehicles, the optimum ratio of pavement concrete with mechanical performance, durability and workability is designed based on orthogonal test. Three load stress levels of 30% and 80% were selected and four different fatigue loading schemes were designed to carry out fatigue tests on pavement concrete. The residual strength and stress-strain curves of pavement concrete under different fatigue loading schemes were measured by MTS, and the mechanical properties of pavement concrete under dynamic fatigue loading were studied by means of the classical fracture energy theory. The results show that the residual flexural tensile strength of pavement concrete decreases by 20% when the stress level is 80% under dynamic fatigue load, and the residual flexural tensile strength of pavement concrete decreases by 20% after 4 hours of loading, and when the load stress level is 30% and 50%, the residual flexural tensile strength of pavement concrete decreases by 20%. In the early stage of dynamic fatigue load, the residual flexural tensile strength of concrete shows negative attenuation, and after 3 hours of fatigue loading, the residual flexural tensile strength of concrete increases by 7.9 and 3.1, respectively, and dynamic fatigue load results in the increase of pavement concrete brittleness. The deformation presents a three-stage attenuation law of "elastic-plastic similar elasticity", and the fracture energy of pavement concrete decreases with the increase of loading time and load stress level. When the stress level is greater than 50, the fracture energy of concrete is obviously degraded by fatigue load, and when the stress level is 3050% and 80%, the fracture energy of concrete decreases by 24% and 66% respectively after 4 hours of loading.
【作者单位】：长安大学特殊地区公路工程教育部重点实验室;路易斯安那州立大学路易斯安那州交通研究中心;
【基金】：国家自然科学基金项目(51608047,51278059)
【分类号】：U414

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